An increasing number of vehicles include a side airbag, a curtain airbags and a seat belt with built-in pretensioner to protect an occupant of the vehicles, the side airbag being configured to be deployed between the upper body of the occupant and a door, the curtain airbag being configured to be deployed between the head of the occupant and the door. In a vehicle having such features, when the vehicle rolls over toward an outer side of the occupant, the curtain airbag is deployed to prevent the head of the occupant from hitting the door.
However, when the rollover of the vehicle starts, the occupant tends to be close to the outer side (door side) of the vehicle. In this case, a gap between the head of the occupant and a vehicle side wall (a door, a glass, a pillar trim, and the like) is small and this causes a problem that the curtain airbag cannot be smoothly deployed.
To counter this problem, Patent Literature 1 discloses an airbag control system configured to control deployment of a curtain airbag. In this system, when rollover of a vehicle starts, a side airbag is deployed and, at the same time, a pretensioner of a seat belt is activated. This moves an occupant to a vehicle inner side (an opposite side to a door) and secures the occupant to a seat thereby providing a gap between the head of the occupant and a vehicle side wall. Hence, the curtain airbag can be smoothly deployed.